This invention relates to a heat exchanger core construction of a type in which the core is formed from a plurality of cut and formed metal sheets which are interconnected to form a completed core structure which can be mounted in the housing with suitable duct work to provide an effective heat exchange system.
Heat exchangers using metal cores are particularly effective in high efficiency of heat transfer and also resistant to high heat value or high pressure values in comparison with cores using plastics materials. One disadvantage of the use of metal sheets for forming the core has however been the relatively high cost of manufacture including folding and forming the sheets into a cell structure, providing suitable spaces for the cells and then assembling the space cells into a unitary core construction.
In many cases welding of the sheets to form the cell structure has been used which provides a very rigid structure which is very resistant to heat and pressure but this is of course a highly expensive process involving much labour.
The present applicant disclosed in U.S. Pat. No. 4,848,450 (Lapkowsky) issued July 18, 1989 an arrangement in which single metal sheets are folded to form upstanding walls at the edges together with a flange which is turned inwardly from the top of the upstanding wall. This structure is then interconnected by sliding each plate member into connection with the flanges of the next adjacent plate member to form an interlocking structure without the necessity for welding or individual spaces.
This construction has been highly satisfactory in producing heat exchangers of a medium and relatively large size and has been used widely for this purpose.
One problem has however arisen with an arrangement of the type shown in the above patent. When the construction is used with very large heat exchangers, the very large plates which are required can cause problems in that even very small inaccuracies in the bending process can cause adjacent plates to be slightly twisted from a directly overlying relationship leading to a core which is twisted that is the corners do not lie on a straight line but tend to twist or lie on a helix thus making it difficult to assemble the completed core into the housing.